This floppy by the shareware and public domain distributor "Explore The World of Software Inc." contains a large collection of Windows 3.1-era icons which are now very difficult to find online.
Note that this disk contains the icons as NE-format DLLs which are no longer supported by 64-bit Windows icon pickers. To use them on modern systems, you will need to extract them using a tool which does not depend on Windows for EXE-parsing, such as wrestool from the Linux icoutils package.
An example wrestool command would be wrestool -x --output=. -t14 *.DLL